When dragging to re-parent in the Outliner, I'm not getting any visual feedback. How do I fix this?
The problem is caused by the Window Draw Method in the User Preferences > System menu. When this is set to "Full", the overlay isn't drawn. Changing it for example to "Overlap" fixes the issue. (however, there are other problems that arise in other parts of Blender when Window Draw Method is not set to "Full")